Photo of an unknown Nokia slider surfaces on the web
It is speculated that the Nokia handset will belong to the X3 Touch and Type lineup, but judging by its form factor it seems to stand nicely as a blend between the Nokia C5-03 and the Nokia C3-01. Some are even guessing that this could be the Nokia RM745, which has been approved by the FCC last week and has similar dimensions. Technical specs remain a mystery though it is supposed that the slider has a resistive or capacitive touchscreen and will probably run Nokia's S40 UI.
source: My Nokia Blog via Daily Mobile